Unloaded chunks has been a major problem for a while, and when in a standard world, an annoying but working fix is for the host to fully restart the client. However, on a realm, it is obviously server-hosted, so one cannot simply restart their client. 

Anywho, I'm playing on a realm I just joined, and I stumble upon some unloaded chunks. My first thought was to try and reload my client, hoping that it was just a client-side error. I was wrong. Upon trying to rejoin the realm, I was met with an indefinite "Building Chunks". Standard troubleshooting does nothing.

The rest of the realm also saw that the chunks were unloaded for them as well, and found that there was no barrier, and blocks were actually behaving, they just had no textures. We tried even kicking me from the realm and rejoining it, and it did nothing.

Other posts don't seem to be describing the issue in the same way that this one is, which is why I'm making it instead of voting for it.